Low pitch rigid frame building



Feb. 3, 1959 H. G.- SIMPSON ETAL LOW PITCH RIGID 6 Sheets-Sheet 1 FiledJune 11, 1957 m m m w.

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LOW PITCH RIGID FRAME BUILDING Filed June 11, 1957 6 Sheets-Sheet 6 IN VEN IORS flare/a 6. 5/ 22/50/7 Norma/7 l V. @mm/ nited States Patentfit'ice 2,871,997 Patented Feb. 3, 1959 has LOW PITCH RIGID FRAMEBUILDING Harold G. Simpson, Raytown, and Norman W. Rimmer, Independence,Mo., assignors to Butler Manufacturing Company, Kansas City, Mo., acorporation of Missouri Application June 11, 1957, Serial No. 665,026

3 Claims. ('Cl. 189-1) This invention relates to rigid frame buildingsand the construction thereof and refers more particularly to low pitchrigid frame buildings comprising one story gable bents of rigid frameconstruction wherein a raftered roof structure is built integrally withWall columns.

This invention is an improvement over and further development ofapplication Serial No. 558,084, filed Jan uary 9, 1956, entitled Columnand Rafter Assembly for Rigid Frame Buildings, inventors Roger A. Hieldand Carmen L. Ramirez, now Patent No. 2,815,831, patented December 10,1957.

Rigid frame structures A rigid frame building is one which isstructurally stable by virtue of the rigidity of its joints, asdifferentiated from a trussed structure which is stable because of thetriangular arrangement of its members. Rigid frame structures of thistype are now quite common and in many building applications havereplaced the ordinary roof truss and column structures of past times.The various frame members of a rigid frame structure are generallyreferred to as the column, the rafter and the knee. The knee is thatarea or joint at the cave which connects the column and rafter memberstogether. The knee ties the structuretogether and makes it a unit tocarry all loads whether they be vertical loads on the roof or lateralloads on the vertical projection of the building.

Rigid frames are arches in their action and they produce a lateralthrust at their bases. In truss-type frames this thrust is not verygreat and can usually be carried by the ordinary type of floor andfooting construction. The rigid frames can be made fixed or free(hinged) at their column base. A hinged column base keeps foundationcosts at a minimum and is therefore generally preferable. Rigid framestructures belong to a general class of structures called continuousstructures. This term is applied because the structural action andstress travel are continuous throughout the structure, there being nojoints in the structural sense. Because of this, the entire structuremust be stress analyzed as an integral unit and cannot be considered asan assembly of separate members.

Rigid frame types of buildings are essentially merely an enclosing shellaround the necessary functions of the building and the structure itselfuses up little of the en closed building volume. Such a constructioncontributes to economy and the useable interior dimensions always governthe outside dimensions of the building. A rigid frame building requiresa height from two to five feet less (depending upon span) than thatrequired by comparable truss and column construction. The structuralframe of buildings of this type when erected and placed present a veryrigid type of construction even before the enclosing walls are in place.The structure is very pleasing to the eye in that it is clean and clearcut. The absence of the usual maze of steel members found in atruss-type construction is notable.

Rigid frame buildings are designed for live and wind loads plus deadload. Dead load is the weight of the building itself. Live load can beany load that can be applied to the building but is usually thought ofas snow load and is considered as acting vertically over the horizontalprojection of the room. Wind load is also a live load but is consideredseparately because the wind load is considered to act horizontally onthe vertical projection of the building. load on buildings will vary foreach different size and shape and that the wind load will act as apressure on'the windward side and as a vacuum on the leeward side of thebuilding.

The principal stresses of a rigid frame are due to bending. The shearsand thrusts are of little consequenceexcept that the direct compressionin the column and roof beams is usually an appreciable stress. The kneeis the strongest section of the frame. This condition is required byvertical load considerations, but at the same time gives the frame avery great lateral strength. Since the knee is always the sectionrequiring the greatest strength it has greater depth than any otherpoint in the frame. The structural performance of the knee section israther complex in that there is a sudden change in the direction ofstress in traveling around the sharp corner between the column and therafter members. However, the design of the knee has been wellestablished on a rational basis by a considerable number of tests, someof'them relatively large sized members. These tests indicate a nonlinearstress distribution around the corner with the neutral axis displacedtoward the inside corner of the knee. 7

It should be especially pointed out that in every rigid frame or arch,no matter what the size or configuration of the column and raftermembers, there is a moment diagram which has certain features common toall. This diagram consists in (assuming the column hinged at the base) amoment increasing up the column uniformly to the knee joint where thereis a change of direction into the roof beam. This moment in the columnis a negative one with the inside of the column under compression andthe outside of the column under tension. The neutral axis where there isno'compression nor tension runs up the center line of the column.Starting at the roof beam or rafter at the knee joint there is a maximumnegative moment which decreases to zero at some point before the centerpoint or ridge of the building which then becomes positive until theridge. The point of zero moment in the rafter is called the point ofinflection. While the moment diagram for any given structure can bemodified by changing the stiffness of the various members at variousplaces, nevertheless, this general pattern is constant although thepoint of inflection may shift.

Rigid frame structural member In the rigid frame buildings ofconventional construction, the main frame members are generally L-shapedcolumn and rafter members, the L-shaped members being used in opposedpairs which are joined at the ridge of the roof. In such L-shapedmembers, the web is preferably widest at the junction between the columnand the rafter since this is the point at which the load and stressesare the greatest. The column tapers downwardly from this point and therafter likewise tapers toward the ridge, all in accordance with goodengineering design.

A few manufacturers of prefabricated buildings make the entire L-shapedmember (one column and its attached rafter) as a single integral unit.However, this presents a tremendous storage problem at the factory, notto mention the problem of shipping such units to the site where thebuilding is to be erected. Accordingly, it is more common practice tomake this member in two parts which are assembled at the job site.

In such a conventional two-piece construction, one of Wind tunnel testsshow that the wind the parts is a conventional I-beam section and theother is an elbow-shaped column and hauneh section, the two being joinedby a bolted or riveted splice plate. This is the situation in the W. B.Larkin et al., Patent No. 2,263,214, entitled Rigid Frame Building,issued November 18, 1941. This is a material improvement but the columnand haunch section still is a cumbersome unit to store and ship. Also,since different builders have different ideas about what the wall heightof their building should be (which means that the column portion must bemade longer or shorter, according to the builders requirements), thefactory must maintain a variety of sizes of haunch sections, each sizebeing specially designed and engineered at no little expense.

A few manufacturers have endeavored to make the column and the rafterseparate parts which are joined at the job site by means of a largesplice plate, but this is the point of greatest load and strain, and,therefore, requires a big splice plate and a very large number of rivetsor bolts to obtain the necessary strength. On the whole, thisarrangement is not very popular or satisfactory with the manufacturers.

In the Hield and Ramirez application Serial No. 558,084, above listed, acolumn and rafter assembly was provided wherein the column and rafterwere separate, straight structural members formed to permit a stable,strong interconnection therebetween which was simple, small in size andrequired a minimum number of interconnecting bolts or rivetstherebetween. This construction obviated the manufacturer having tostore and ship elbow-shaped haunch sections.

The latter construction proved to be satisfactory for limited widthbuildings and buildings having a relatively steep pitch, say, in a ratioof one to six or the like. However, when it became desirable toconstruct extremely wide, low pitch, rigid frame buildings, pitch ratioof one to twelve, the construction provided therein proved to beunsatisfactory for a number of reasons. In the first place, it is wellknown that the lower the pitch of the building the higher the bendingmoment at the juncture between the column and rafter. It proveduneconomieal or impracticable to insert enough bolts in thecolunm-rafter juncture to carry the moment stress. In the second place,since it was desired to employ column and rafter members tapered tocorrespond to the areas of greatest moment it was found that as thewidth of the building increased, the tapering of the rafter members hadto be much more gradual to provide a strong enough central joint and,thus, the construction provided little advantage over a uniform crosssection I-bcarn. In either the uniform cross section f-beam or in such auniformly tapered rafter member, it was discovered that there wasexcessive strength at points in which strength was not required, thuswasting material and, additionally, in the tapered member, there wasrelatively low central strength. Finally, it proved desirable toassemble the low pitch, wide, rigid frame building by first erecting thecolumns and then picking up the entire rafter member connected as onemember centrally thereof and setting it on the columns to be attachedthereto. A uniform cross section I-beam proved to be of greatlyexcessive weight (particularly because of the excess steel in the web)while a uniformly tapered member was of insufficient strength centrallythereof to permit such an operation. Other factors desired included theprovision of a uniform roof line to permit fixing of rigid panelsheeting thereto and a relatively uniform rafter underside to permitfixing of an adequate ceiling thereto, as well as providing a buildingwhich could be completely and adequately weatherproofed both fromvertical weather effects and from horizontal weather effects.

Therefore, an object of this invention is to provide a rigid frame,one-story gable bent of an extremely low pitch and of relatively greatwidth wherein the column and rafter members are designed to provide thegreatest &. practical efiiciency in withstanding bending moment stress.

Another object of the invention is to provide such a rigid framebuilding wherein the structural support members may be erected by firstsetting up the columns and then lifting the previously connected raftermember upwardly as a unit, while suspending it from its center andsetting it on the columns to be fixed thereto, the rafter member beingsufiiciently strong to withstand this central suspension while, as well,being of an absolute minimum weight to facilitate the operation.

Another object of the invention is to provide a column and rafterassembly for a low pitch, maximum width, rigid frame building of theone-story gable bent type wherein the column and rafter members areformed so as to provide the maximum resistance to bending moment stressyet wherein the roof line is uniform to permit application of straightsheeting thereto and the ceiling line is harmonious and simple to permitthe application of a suitable ceiling.

Another object of the invention is to provide a low pitch, extremelywide, rigid frame building of the onestory gable bent type wherein aplurality of types of building end column and rafter members may beemployed to minimize both in each member and the combination thequantity of metal required and the engineering required in the buildingwhile still providing an extremely strong and rigid building with all ofthe advantages both engineering-wise and appearance-wise of rigid framebuildings.

Yet another object of the invention is to provide a low pitch, extremelywide, rigid frame building of the onestory gable bent type, theconstruction of the utmost simplicity yet providing a completelyweather-sealed construction against both vertical and horizontal weathereffects.

Another object of the invention is to provide a low pitch, extremelywide, rigid frame building of great strength, rigidity, inside volumeand weather tightness which is yet of the utmost simplicity and may beconstructed at great speed and at a minimum cost.

Other and further objects of the invention will appear in the course ofthe following description thereof.

In the drawings, which form a part of the instant speeification and areto be read in conjunction therewith, an embodiment of the invention isshown and, in the various views, like numerals are employed to indicatelike parts.

Fig. l is a perspective view with parts broken away showing a wide spanrigid frame building of the onestory gable bent type of the inventiveconstruction.

Fig. 2 is a side view of one of the inventive column and rafterassemblies.

Fig. 3 is an end view of one form of the end of the building from theoutside of the building, this form applicable to buildings whereinfurther expansion is not contemplated.

Fig. 4 is an enlarged side elevation of one of the column and raftermembers of Fig. 2 as mounted as an intermediate member in the inventiverigid frame building.

Fig. 5 is a schematic diagram of the moment diagram of a column andrafter unit of one of the inventive buildings.

Figs. 6ll are all detail views of parts of the construction shown inFig. 1. All of the viewsare in the same perspective as Fig. l, enlarged,in the direction of the arrows in Fig. 1. Fig. 6 is a view taken alongthe lines 6-6 of Fig. 1 in the direction of the arrows.

Fig. 7 is a detail view of one of the joints between the roof purlinsand the sag angles of Fig. 1 as taken along lines 77 of that figure inthe direction of the arrows.

Fig. 8 is an enlargement of the center joint of the inventive column andrafter assembly showing the attachment of the brace rods and struts tothe center thereof as taken along the lines 8-8 of Fig. 1 in thedirection of the arrows.

the middle to form a rafter member.

Fig. '9 is a detail view of the upper front right corner of the buildingof Fig. 1 taken along the lines 99 of Fig. 1 in the direction of thearrows.

Fig. 10 is a view of the lower right-hand front corner of the buildingin Fig. 1 taken along the lines 10-10 of Fig. 1 in the direction of thearrows.

Fig. 11 is a detail view of the joinder between the girts and the columnin the right-hand front corner of the building of Fig. 1 taken along thelines 1111 of Fig. 1 in the direction of the arrows.

Fig. 12 is a detail perspective view of the juncture between the lowergirt and door post on the right-hand side of the door of Fig. 1 takenalong the lines 12-12 of Fig. 1 in the direction of the arrows.

Fig. 13 is an enlarged detail View of one end of a roof purlin and theattached gable angle taken along the lines 13--13 of Fig. 1 in thedirection of the arrows.

Fig. 14 is a side view of a second form of the end of the building fromthe outside thereof, this form particularly applicable to buildingswherein expansion is contemplated or the end wall is to be open.

Fig. 15 is a three-quarter perspective view of a connection between theroof beam and the end wall post of Fig. 14.

Fig. 16 is a three-quarter perspective view of a connection between apurlin and the gable angle of Fig. 14.

Fig. 17 is a three-quarter perspective view of the column and girtconnection of Fig. 14. Fig. 17 is a view taken along the lines 17-17 ofFig. 14 substantially in the direction of the arrows.

Fig. 18 is a three-quarter perspective view of the positive column base,side and end wall floor members and floor of Fig. 14. Fig. 18 is a viewtaken along the lines 18-18 of Fig. 14 substantially in the direction ofthe arrows.

General building construction Referring now to the drawings and moreparticularly to Fig. 1, numeral 20 indicates generally the flooring forthe building which may conveniently be a poured concrete slab. Themargin of the slab comprises a curb 21 having a downwardly extendingedge which, in the construction shown, provides a sill 22 for theforward door. If it is desired that the floor 20 be below the top of thecurbing 21, the floor or foundation may be poured in a shallowexcavation conforming in size and shape with the desired dimensions ofthe building, and the curbing 21'be formed in the usual manner by formswhich can be knocked down and removed once the concrete is set. On theother hand, if the curbing and the floor are desired to be at the samelevel, the flooring may be poured within forms itself to raise it abovethe level of the supporting surface for the building whereby to providethe curb 21. Various floor and curb constructions may be used so long asa curb having a downwardly extending edge is provided.

Providing the main supporting structure for the side walls and roof arethe arch-like support members which are spaced at intervals along thedepth of the building and span the width thereof. In the construction ofFig. 1, there are shown two types of arch-like floor spanning supportmembers, the one at the front (and the one at the rear of the buildingnot shown) comprising straight columns supporting straight membersarched to join at Centrally of the building of Fig. 1 there is shown anarch member having tapered columns, tapered haunch members and reversetapered central members. This construction is shown in Fig. 2 as anintermediate member, in Fig. 14 as an end member, and will be describedin more detail later. The combination in a building of strongercentralmembers and weaker end members as in Fig. 1, comprises amodification of the invention for use when expansion is not contemplatedand the combination of solely high strength rigid frame members as inthe center member of Fig. l r

and end member of Fig. '14 is employed in buildings wherein expansion iscontemplated or the end walls are to be open.

The untapered arch end elements as in Fig. 1 (see Fig. 3 as well)comprise relatively stright column members 23, I-beams in cross section,and relatively straight, untapered rafter members 24, also I-beams incross section. Rafters 24 are fixed to the tops of columns 23 by bolts25 penetrating the flanges on the underside of the rafter member and anextra flange 23a on top of the column 11. The outer ends of the raftermembers 24 extend past the outer flanges of the columns 11 at least adistance equal to the distance which the columns are inset from the edgeof the curb 10a. The I-beam flanges are closed at both their outer andinner ends as at 24a and 24b by extra flanges joining the upper andlower flanges thereof. The inner ends of the rafter members 24 abut at aridge as shown at 26 and flanges 24b are welded or bolted togetherthere. Referring to Fig. 10, which shows the detail of the right frontcolumn at the corner in Fig. 1, it may be seen that the column 23 has aclosing lower flange 23b which is fixed to the concrete curb 21 or floor20 by bolts 27. The column is set in from both the side and front edgesof the curb tionally, the arches of Figs. 4 and 14 will be numberedalike in their identical elements. As in the previously.

described untapered arch element, the column and rafter members of thetapered element are I-beams in cross section. Vertical column 28 istapered from a lesser depth adjacent the bottom thereof to a greaterdepth adjacent the top. Column 28 has horizontal plate 29 joining theI-beam flanges on the top thereof with a portion of said plate 29extending outwardly beyond the outer flange of the column 28 a distanceequal to the distance which the column is inset from the curbing edge.Gusset 34 may connect the underside of the plate extension to the columnouter flange for support. Outer haunch member 31 is attachable to thetop of the column at its outer end and angles upwardly inwardly towardits inner end. A portion of the lower I-beam flange of the outer haunchmember 31 is angled from the line of the lower flange to form ahorizontal plate 32 to match and be engaged with the horizontal columnplate 29. The web of haunch 31 extends beyond the outer edge of thecolumn 28 to the vicinity of the outer edges of the column and haunchhorizontal plates. Flange 33 at the outer end of the haunch 31 joins thehaunch upper flange and the lower horizontal plate to furnish additionalstrength in the end of the haunch. Additional stilfeners 34 (optional)and 35 (essential) are generally added to aid in strengthening thehaunch at the joint. Stiffener 35 prevents crushing or bending of theweb at the critical point of stress, while 34 is extra for high loadoperations. Flange 33 is normal to the web of the haunch. One set ofbolts (32aFig. 4) may engage the column horizontal plate 29 and haunchhorizontal plate 32 outside the outer flange of the column and anotherset of bolts (32b-Fig. 4) may be positioned through these two plates atthe inner edge of the column whereby to connect the column horizontalplate and haunch horizontal plate to form an essentially rigid jointtherebetween. The column 28 web preferably increases in depth upwardlyand the haunch 31 another by bolts 38 (not visible in Fig. 14, see Fig.8) engaging the central vertical splice plates 36a thereof. The centralflanges 36a preferably extend upwardly above the upper I-beam flanges ofthe central beams 36 as at 36b. Bolts 39 are fitted through these upwardextensions and a flange opening 40 extends therethrough.

For any given building structure, considering dead load only, the depthof the webs in the column members, haunch members and central beams arepreferably proportional to the moments therein and the joinder betweenthe central beams and the haunch members is preferably as close to thepoints of inflection in the moment diagram as possible.

It should be pointed out that, so long as the depth of the web of thecenter beam members 36 is proportional to the bending moment therein, itdoes not matter whether the upper flange of the center beam members isin line with those of the haunch members or whether the lower flangethereof is positioned in any particular way relative the lower flangesof the haunch members. However, it is preferable that the upper flangeof the center beam members be substantially in line with the upperflanges of the haunch members so the purlins may be of the same size (incross section) so the roof sheets may be and lie flat. Of course, withthe center beam taper, it is impossible, if the upper flanges of thecenter beam members are in line with the upper flanges of the haunchmembers, for the lower flanges of the center beam members to be in linewith the upwardly inclined lower flanges of the haunch members.Therefore, preferably the lower flanges of the center beam members areessentially parallel with the floor or slightly cambered whereby to givethe appearance of a flat rather than a sagging ceiling. The upperprojection of the center (ridge) beam splice plates 36b serves as acompression joint,'takes tension during the erection of the building andunder wind load. The thickening of the beam downwardly also preventsthis plate from extending downwardly, the width of the plate beingnecesary to space the bolts joining the center beams a certain distanceapart.

Referring back to Figs. 1 and 3 and the general description of thebuilding employing an untapered and frame element, a plurality of endwall posts 41 are fixed to the rafters 24 by clips 42 and are bolted attheir bottoms to the floor 20, as are the columns in Fig. 10, inset fromthe curb slightly. Door posts 43 are preferably C-shaped in crosssection with their outer flanges in line with the outer edge of thecurb.

Sets of diagonal brace rods 44, 45 (side), 46 and 47 (front), eachprovided with an intermediate turnbuckle, are provided between at leasttwo adjacent arch elements on a side and two adjacent front posts orrear posts on the front and rear sides of the buildings for bringingthese members into, and maintaining them in parallel relationship.Likewise, in the roof, a plurality of sets of tie rods (unnumbered) areprovided for the same purpose relative adjacent arch elements. Figs. and8 show the manner of fixing these tie rods relative the columns and thebeam members, respectively. 8, tie rod 44 is thus fixed to the column 23by plates 48 engaged by bolts 49. In Fig. 8, brace rods 59 and 51 arefixed by clevises to the clip 52 of strut 53, the whole assembly beingfixed to the central beam central flanges by brace rod clip 54 by meansof bolts 46.

Girts 56 extend lengthwise of and across the ends of the building onopposite sides thereof, are preferably Z-shaped in cross section (Fig.4) and are secured to the outer flanges of the columns and end posts 41intermediate the upper and lower ends thereof. Sag rods 57 depend fromthe cave members to be described, to suspend the center section of thegirts 56. Girts 56 are secured directly to the vertical columns of theframe members, either by welding or by bolts. Fig. 11 shows the junctureof the side and end wall girts of the right front end wall column ofFig. l. Girt column clip 58 is affixed to the outer flange of the columnby bolts 59 and the front and side girts are attached thereto by bolts60 and 61, respectively. Fig. 17 shows side and end girts 62 and 63fixed relative the heavy duty end wall column by girt column clip 64 andbolts 65 and 66, the clip itself fixed to the outer flange of the columnby bolts 67. Clip 64 has angle 68 fixed thereto to provide backing forthe corner panel to be set thereagainst out to its edge.

in F l and 3, the roof purlins 69 are also preferably Z-shaped in crosssection and like the girts, span the distance between adjacent framemembers. The ends of the purlins rest upon, and are secured in anysuitable fashion, such as by bolts, to the upper flanges of the raftermembers. Transverse sag angles 70 are utilized to connect theintermediate portions of adjacent purlins and maintain them in parallelrelationship. As seen in Fig. 7, the sag angles 70 have crimped ends 71engaging slots '72 in the purlins. The ends of the purlins 69 areattached to gable angles, to be described, by angle clips 73 (Fig. 13)bolted to the purlins at 74 and the gable angle at 75.

As may be seen in Figs. 3, 4 and 9, the eave purlin members 76 areC-shaped in cross section which are secured to the outer ends of therafters. Eave corner closures 77 (Fig. 9) carry the cave members out tothe limit of the curbing and join the gable angles.

Referring to Fig. 4 particularly, flange braces 78 are employed toprovide lateral support for the inside flanges of tapered arch elementsemployed within the building in the columns, haunch members and centralbeams. Braces 78 are fixed at their outer ends to the girts or purlins,respectively, and at their inner ends to the inside flanges of thevarious members.

Back to Fig. 1 and also looking at Fig. 12, the door jamb is formed bydoor posts 43, the girts 56 on the front of the building being fixedthereto by means of clips 79 welded or otherwise attached to the insideof the door post columns. Bolts 80 connect clips 79 and girts 56. Thedoor posts 43 also carry at their upper ends horizontal header 81(U-shaped in cross section) which is also supported by clips 81a (Fig.6) connected to each of the end wall posts 41. Stabilizing flanges 81b(Fig. 6) prevent rotation of posts 41 and are fixed to the front flangethereof by bolts 810. Fig. 9 shows the end supports for header 81, aclip mounted on the web of the rafter member 24. Bolts 83 connect theclip and the header 31. The front girts 56 are bolted to the frontflanges of the end wall posts 41. The front sag rods 57 are carried bythe horizontal header 81. The front girts and the horizontal header 81are positioned with their edges or outer flanges essentially in linevertically with the outer edge of the curb 21 at the front.

A gable angle (-Figs. l, 13) extends outwardly from the top edge of thefront and rear rafter members whereby to be in line with the curb 21supported by the gable angle clips or plates 73 (Fig. 13) and the cavecorner closures 7 (Fig. 9) which are fixed to the roof purlins 69 andthe end eave members 76, respectively. Gable angle 75 has its outer facesubstantially vertically in line with the outer face of the curb 21.

The side walls of the building are formed by a plurality of corrugatedrectangular panels 35 which are fastened to the framework of thebuilding in the manner most clearly shown in Fig. 4. Each panelpreferably comprises a fiat metal sheet having formed therein threespaced parallel corrugations, a center corrugation and two outercorrugations which form the outer edges of the panel. An interlockingarrangement between adjacent panels is obtained by nesting thecorrugations at the edges of the panel one within the other to give theappearance of a continuous single panel arrangement. The nestingcorrugations may be provided with bolt apertures for the insertion ofbolts to obtain a more rigid connec tion between panels.

As shown in Figs. 1, 3 and 4, the length of the side wall panels ispreferably slightly greater than the height of the side wall of thebuilding. The upper ends of the side wall panels are bolted to the eavemembers 76, the intermediate portions are bolted to the girts 56, andthe lower ends of the side wall panels are bolted in like fashion toangle irons running around the edge of the curbing as in Fig. 10. Number86 indicates the panel receiving angle irons, 87 the side angle ironclosures, and 88 the corner closures. Theangle irons 86- 88 are securedon top of and along the outer edges of the curbing 21. It will be noted,particularly from Fig. 4, that the lower ends of the corrugations areclosed by flattening the ends of the corrugations against the panelsheets as at 85a. The same is done both above and below any windows inthe building. The lower terminus of each corrugation along the lengthand across the width of a building is flattened or crimped in thefashion shown, thus providing a weather-tight connection with thefoundation. Preferably, the panels themselves extend down to a levelslightly below the angle irons 8688 to abut with their inner faces theface of the curbing, thereby providing a complete weather-tight seal.The upper ends of the wall panels are mitered to fill the corrugationsin the roof panels in weather sealing fashion.

The roof of the building is formed in much the same manner as the sidewalls. As is true in the side walls, the roof panels have interlockingcorrugations and are disposed in interlocking side by side arrangementalong the length of the building. However, each side of the roofpreferably comprises three panel sections, namely, an outer eave panel89 having a downwardly curved portion 89a extending beyond the side wallof the building; a flat intermediate roof panel 90 overlapping at itslower end the upper end of the cave panel; and a one-piece ridge panel91 having angularly disposed portions extending downwardly from theridge line of the roof on opposite sides thereof which overlap at theirlower ends the upper ends of the intermediate panels; The jointsprovided by the interlocking corrugations lengthwise of the building andthe overlapping relation between adjacent panels from the eave to theridge line are made weather-tight by application of mastic and preventleakage, even under the most severe conditions. The panels are securedto the framework of the building (eave members 76 and roof purlins 69)by bolts located at suitably spaced intervals.

It should be noted that the joint formed by the intersection of the sidewall panels with the eave panels is effectively shielded by thedownwardly curved portion of the latter in combination with the sidewall mitering. Even in strong winds, snow or rain, it is effectivelydeflected away from the joint and there is little or no possibility ofintrusion. Also, by virtue of the single piece ridge panel, no joint isformed along the ridge line of the roof and leakage is thus impossiblein this area.

It should be understood that while in Fig. 1 only a portion of thebuilding is shown as paneled, in its completed form itis completelycovered with the exception of the doors and windows. The window 92 shownin Fig. 1 has no critical construction and will not be described indetail.

In forming the end walls, side wall panels may be employed to cover theentire front of the building abutting and bolted to the horizontalheader 81 at their upper ends and the outside face of the curb with theinner faces of their lower ends, the panels also being bolted to thegirts at suitable intervals along their length. The header 81 ispositioned at precisely the same height as the C-shaped eave member 76whereby the same height panels may be employed around the entirebuilding. This is a substantial advantage of the design. In

forming the end walls,it is necessary to superimpose upper panelsections over the upper end of the conventional side wall panel toobtain the required height. The upper edge of the upper panel sectionwill of course be cut along the line conforming to the pitch of theroof. The upper end panel sections communicate between and are fixed tothe horizontal header 81 and the gable angle 75. To fill the spaces overthe door, pieces of the required configuration can be cut from the basicpanel.

The end Wall construction to support the front or rear panel sheets whena heavy duty frame member is employed, as in Fig. 14, has manysimilarities to, but some differences from the already described endwall construction of Figs. 1 and 3 illustrating the front door wallemploying the light duty beam member.

In Fig. 14, the parts which are analogous to the showings in Figs. 1, 3and 613 are numbered like the parts in these figures but are primed todistinguish them. Those parts which are not analogous to the showings inthese figures are given new numbers.

Thus, referring to Fig. 14, we see end wall posts 41', side girtsalready numbered 62, horizontal header 81', and sag rods 57'. Since therigid frame arch element shown in Fig. 14 is the same as the rigid framearch element which is tapered in Figs. 1, 2 and 4, the parts of thismember are numbered the same as in these other figures but primed aswell. Additionally, the roof purlins are numbered 69 and primedanalogous to the showing in Fig. 3. The eave member is numbered 76 andprimed. .The clips connecting the horizontal header to the end posts 41are numbered 81a and the flange members as sociated therewith 81b.

Referring to Fig. 18, this showing is analogous to the showing of Fig.10, but from a different perspective. The foot of the tapered column 28is fixed to the floor 20' by bolts 93. The edge angle irons include thecorner angle 94 and the side angle irons 95 which are all bolted to thecurbing and in line therewith. These pieces receive the inner faces ofthe panel sheets in the same manner as the angle irons 8688 of Fig. 10do.

The mounting of the girts has already been described relative Fig. 17with numerals 6468.

, Referring to Fig. 16, the construction of the gabl angle supports isanalogous to the showing of Fig. 13 but in Fig. 16 two supportingmembers 73' connect the gable angle 75 to the purlins 69. These piecesare bolted to one another and the gable angle and the purlins 69.

Fig. 15 shows the manner of attachment of the end posts 41' to thetapered beam 36' (or 31). A plate 41a is welded to a cutaway section ofthe top of the I-beam end posts. Plate 41a is engaged by an H-clip 96which in turn is bolted to the web 'of the beam 36'. This is the mannerof attachment also of the end posts of Fig. l to the rafter memberalthough such a detail was not shown.

In describing the assembly of the building, Figs. 2 and 8 should bereferred to as the former shows the entire tapered, rafter element andthe latter. shows the perforation in the upwardly extending plates 36bof the center beams. The rafter element is first completely assembled onthe ground with the center beams 36 bolted to one another and theirouterends fixed by the plates 37 to the tapered haunch members 31. A pin (notshown) is inserted through the opening 40 in the plates 36b and theentire assembled roof beam may be lifted as a unit by a crane or thelike. Before the rafter element is lifted, the columns and end posts areerected and fixed relative one another by the girts 47. The entirerafter unit is then lifted and placed on top of the columns to which itmay be bolted. The roof purlins may then be put on and the tie rodsattached on the side and end Walls as well as the roof. The length ofthe building and the internal strength required will dictate the numberof tapered rigid frame members that are required and whether such aredesired as end frames. In the illustrated embodiment of Fig. 1, thereare only three arch frame members in the building, only one of them (thecentral one) a rigid frame member. If desired, the rear frame arch couldbe tapered as in Fig. 14 and/or the front arch member as well.

Forces in the building The frame itself is a rigid structure. joints atthe ridge and the cave are rigid and not hinged. In the structuralanalysis of the building, the points of attachment of the frame to thefoundation are treated as though they were hinged. This is not strictlycorrect, but the narrow width of the column base and the smail anchorbolts offer little fixation and the concrete foundation prevents lateralmovement. So, the frame is essentially a two-hinged arch. The thicknessof the columns in the light duty modification of the end frame membersis preferably essentially that of the bottom of the heavy duty columnmembers. Thus, both types of the column members are treated as hinged tothe same degree.

There are several forces to which a building is subjected. These are itsown weight, snow load on the roof, wind load on the vertical projectionof the building, etc. For the purposes of engineering analysis, theseare resolved into three forces or effects; moment (or bending moment),thrust and shear. The simplest analysis of a rigid frame is that of adead load, taking into account only the weight of the building itself. Auniformly distributed roof load such as snow merely results in a uniformincrease of the various forces. However, a wind load applied to one sideof the building results in eccentric loading with a positive moment inthe column to which the wind is applied and a negative moment in theopposite column. In the following discussion, dead loads only will beconsidered.

First, considering the moments developed in the various parts of thestructure (Fig. since the column is presumed to be hinged at the base,it is free to rotate at this point and there is no bending moment.Moving up the column, the moment increases uniformly to the knee jointwhere there is a change of direction in the roof beam. This moment inthe column is a negative one with the inside flange of the column undercompression and the outside flange of the column under tension. Theneutral axis where there is neither compression nor tension runs up thecenter line of the column. Since the moment varies uniformly from amaximum at the top to zero at the bottom, the column can becorrespondingly designed wide at the top and narrow at the bottom. Theknee joint is rigid, so the moment developed in the roof beam at thisjoint must equal that developed in the column and must be in the samedirection. Starting at the roof beam at the knee joint where there is amaximum negative moment, in the progression up the roof beam or raftertoward the ridge, the moment decreases until it becomes zero (point ofinflection) at some point between the knee and the ridge. As previouslymentioned, this is preferably the point of juncture between the centerbeams and the tapered haunch members. It then becomes positive andremains so until the ridge is reached. The neutral axis of the roof beamlies on or near the center line. At the knee joint where the forceschange direction, the neutral axis tends to pull in toward the insideflange. Although the forces flow continuously through this joint, theirexact distribution depends on the type of the joint.

Thrust in the column is uniform and is directed downwardly into thefoundation. The thrust in the roof beam is directed along its axistoward the knee and increases uniformly from the ridge to the knee.

The shear in the column is directed perpendicularly to the axis of thecolumn. Since the base of the column is That is, the

restrained from lateral movement by the foundation bolts, the upper partof the column tends to shear outwardly from the lower part. Byconvention this is called positive shear. In the column this shear isuniform. The shear in the roof 'beam is directed perpendicularly to theaxis of the beam and varies uniformly from a positive shear at the ridgeto a negative shear at the knee. At the ridge, the beam is restrained bythe joints of the part of the beam away from the ridge and tends toshear downwardly from the part near the ridge. By convention this ispositive. As the knee is approached, the opposite condition prevailsbecause the part furthest from the ridge is restrained by the kneejoint. Under this condition, the part of the beam farthest from the knee(nearest the ridge) tends to shear downwardly from the part nearest theknee. By convention, this shear is negative.

The forces of thrust, shear and moment in the roof beam are transmittedthrough the knee joint into similar but not equal forces in the column.That is to say, thrust in the roof beam does not equal thrust in thecolumn nor does shear in the roof beam equal shear in the column. Asstated previously, the moment of the column at the knee joint equals themoment at the roof beam at the same joint.

When the means which join the column and haunch horizontal platestogether are in part positioned in the portions of the assemblyprojection beyond the outside of the column flange and in part adjacentthe inside of the column, a vertical loading of the rafter tends to pr0-duce a moment so that the outermost joining means are under tension andthe innermost joining means are in compression. A horizontal load on theoutside face of the column or side wall of the building tends to producea reverse moment whereby the outside joining means are under compressionand the innermost joining means are under tension.

From the foregoing it will be seen that this invention is one welladapted to attain all of the ends and objects hereinabove set forth,together with other advantages which are obvious and which are inherentto the structure.

It will be understood that certain features and subcombinations are ofutility and may be employed without reference to other features andsubcombinations. This is contemplated by and is within the scope of theclaims.

As many possible embodiments may be made of the invention withoutdeparting from the scope thereof, it is to be understood that allmaterial hereinabove set forth or shown in the accompanying drawings isto be interpreted as illustrative and not in a limiting sense.

Having thus described our invention, we claim:

1. A column and rafter assembly for a low pitch rigid frame building inwhich the assembly provides a continuous, rigid arched frame structurefor the building comprising a pair of vertical columns spaced laterallyfrom one another and having flat, horizontal mounting surfaces at theirupper ends, and an arched, unitary rafter member extending between andbridging the space between the columns and forming a ridge therebetween,said rafter member being of I construction throughout its length withupper and lower flanges defining the upper and lower flanges of therafter member, said rafter member being symmetrical with respect to theridge, the upper flanges on opposite sides of the ridge extendingupwardly and inwardly in converging planes from the outer end", thereofto the ridge, the lower flanges at the respective outer ends beinghorizontal and in face to face contact with the said mounting surfacesand rigidly secured thereto whereby the beam moment due to dead load andon each side of the ridge reverses at a point intermediate the columnand ridge, the lower flanges extending upwardly and inwardly from theinner edges of the columns to said reversal point at a pitch greaterthan the pitch of the corresponding upper flange whereby the upper andlower flanges converge for a distance inwardly of the columns onopposite sides of the ridge, the lower flanges extending from each saidreversal point to the ridge at a pitch less than the pitch of theoverlying upper flange whereby the flanges diverge from the saidreversal points to the ridge, and the depth of the rafter between theflanges at the ridge and adjacent thereto being snfficient as to providethe rafter member with a cross sectional moment of inertia wherebysuspension of the rafter at the ridge with the ends hanging free andunsupported can be carried out without damage to the rafter member thusto render the rafter member installable on the columns by providing asingle lifting force at the ridge.

References Cited in the file of this patent UNITED STATES PATENTS2,815,831 Hield et al. Dec. 10, 1957 FOREIGN PATENTS 16,127 GreatBritain of 1894

